Stiffening uppers of shoes



Jan. 30, 1951 J. J. BRoPHY 2,539,608

S'IIFFENING UPPERS 0F SHOES 2 Sheets-Sheet 1 Filed May 5, 1949 Jan. 30, 1951 J. J. BRoPHY STIFFENING UPPERs oF sHoEs 2 Sheets-Sheet 2 Filed May 5, 1949 III i. Y y

Patented Jan. 30,' 1951 STIFFENING UPPEBS OF SHOES John J. Brophy, Salem, Mass., alsignor to United Shoe Machinery Corporation, Flemington, N. J., a corporation of New Jersey Application May 5, 1949. Serial No. 91,607

Claims.

This invention relates to stiffening selected portions of the uppers of shoes and is herein set forth in connection with stiffening the toe portions and the rear portions of uppers.

It is common to provide a toe stiffener blank, usually one having a fabric base impregnated with a stiffening substance, which can be softened and rendered limp by treatment with a solvent or with heat; to incorporate the softened blank in an assembled upper; and then to conform the upper with the softened blank to a last, the blank becoming hard and resilient upon evaporation of the solvent or upon dissipation of the heat.

There are certain disadvantages involved in the use of stiffener blanks of the general type outlined above. They can be most conveniently incorporated in the assembled uppers, and are usually so incorporated, just prior to the pullingover operation, a special solvent-applying or heat-applying apparatus being provided for rendering them temporarily limp. They become hard and resilient as soon as the solventl has evaporated or the heat dissipated; but it is difficult to maintain them limp, and hence in condition for being conformed to the last, for just the right time, and then to have them become hard soon afterward so that the last may be removed from the upper. These and other disadvantages present very considerable difiiculties to the. use of such blanks as counter stiffeners so that, although toe stifleners of the general type under discussion are widely used, no shoe manufacturer, so far as I am aware, uses them as counter stiffeners.

The patent to Schwartz No. 1,215,875 of February 13, 1917, discloses a method intended to avoid the disadvantages involved in the use of stiffener blanks which are given a preliminary treatment to render them soft and limp before they are conformed to the last. This patent discloses a method which comprises the use of a stiffener blank carrying shellac in powdered or broken form, whereby the blank is limp when cold and dry. Such a stiiener blank is incorporated in the assembled upper of a shoe and conformed to the last. After the shoe is lasted, the part of the upper which contains the stiffener blank is subjected to radiant heat to fuse the shellac whereby the particles of shellac are caused to run together so that, when the shellac hardens, a stiffened portion of the upper results. Shellac is not a satisfactory material for use in stiffening portions of the uppers of shoes; and subjecting the selected portion of the upper to radiant heat for approximately an hour at a temperature between 210 and 250 F., as is necessary in the patented process, is extremely injurious to all but a very few kinds of leather. Consequently no one, so far as I am aware. has ever made use of the Schwartz process, said patent never having advanced at all the art of shoemaking.

According to the present invention there is incorporated in a selected portion of the upper, in unheated, dry, limp form, stiffener material comprising a themosetting resin which is soft or fluid when heated, for example, a resin obtained by condensation of a phenol and an aldehyde. The selected portion containing the stifener material is then conformed to the shape in which it 1s to be stiffened, for example, by lasting the upper, and subjected to the heating effect of a highfrequency eld to convert it to a tough, strong, resilient condition. The high-frequency eld generates heat directly in the stifener material so that the material is heated rapidly without the necessity of transmitting heat through the layers of the assembled upper. The field need be applied for only a very short interval; there is no danger of injuring the upper of a shoe such as is present when radiant heat is used, and a stiflener material having a comparatively high melting or softening point can be employed.

In accordance with another aspect of the invention. the heating rate of the stiiener material may be increased by incorporating with it a substance having certain electrical properties as hereinafter described.

An apparatus for use in carrying out a step of the method is disclosed in divisional application Serial No. 610,110, filed August 10, 1945, now United States Patent No. 2,406,738 of September 3, 1946. This application is a continuation-inpart of my application Serial No. 564,605 filed November 22, 1944, which has now matured into Patent No. 2,492,413, granted December 27, 1949.

Referring to the accompanying drawings:

Fig. 1 is a plan of a toe stiffener blank according to the present invention;

Fig. 2 is a similar view of a counter stiffener blank;

Fig. 3 is a plan of an apparatus for subjecting the front and rear portions of the upper of a lasted shoe to the heating effect of a high-frequency eld, a shoe being shown in place, certain parts of the apparatus having been removed or broken away;

Fig. 4 is a vertical longitudinal section of the apparatus and lasted shoe shown in Fig. 3, the plate 69. which has been removed in Fig. 3, being shown;

Fig. 5 is a perspective of the rear electrode holder with the electrode;

Fig. 6 is a vertical cross section through the rear part of the apparatus and the shoe which are shown in Fig. 3; and

Fig. 7 is a vertical cross section through the forward part of the apparatus and shoe.

The stiifener blanks (Figs. 1 and 2) may be ausaeoe material comprising a thermosetting resin, for

example, an uncured phenol-formaldehyde resin in a. solvent, such, for example, as acetone; treating the impregnated base with a nonsolvent liquid,

such, for example, as toluene, which is miscible with the solvent but is not a solvent for the resin, so as to precipitate the resin in the base; and then drying the sheet.

The procedure outlined above for impregnating a porous sheet by precipitating in its interstices a thermosetting resin may be carried out in any suitable manner, for example, as disclosed in United States Letters Patent No. 1,256,240, dated February 12, 1918, and No. 1,353,599, dated September 21, 1920, both granted upon applicationsof Stanley P. Lovell. The ldry sheet carrying the stiiiener material in precipitated form, if stiller than desired, may be rendered limp or flexible by any suitable treatment. For example, the sheet may be carried between moving belts which makesharp reverse turns over small rolls so as to bend the sheet sharply rst in one direction and then in another; or the sheet may be run through a mangle and thus be rendered limp and flexible by reducing the precipitated stiffener material more or less to discrete particles. After the above treatment the stiiener blanks may be cut out of the sheet.

It may be desired to omit the precipitating step, in which case the solvent may be caused to evapcrate, and the dry sheet containing the stiffener material treated, if necessary, to render said sheet limp. It will be understood that the base, instead of being a separate member, may be some part of the assembled upper of a shoe, for example, the doubler, which has, for example, been cut out of an impregnated sheet. Also, if there is a carrier resin (e. g., Paraplex X100 in Example I), the porous base may be omitted, and limp, easily conformable stiiener blanks produced by spraying a suitable solution of a thermosetting resin in a suitable manner upon a smoothsurface, peeling off the comparatively thick, porous sheet which results when the solvent has evaporated, and cutting out blanks from such a sheet. In any case, there will be incorporated in the upper of a shoe a limp stiilener material comprising a thermosetting resin in uncured form which when heated is soft or fluid and which, while unheated and dry, may be conformed with the upper to a last and may later be caused to set or cure by subjecting it to the heating effect of a high-frequency field. Advantageously, the softening point of the resin will be about 150 C. or lower.

In certain cases I have found it advantageous to impart to the material which is to be incorporated into the upper, a greater susceptibility to the heating effect of the high-frequency field than it normally possesses. It is well known in dielectric heating that, where a material lls the space between the electrodes, the high-frequency electric energy dissipated per unit volume of material per unit of time is represented by the equation:

Pv=21rKoE2fe' tan 1) where:

Ko=the capacitance per unit cube of free space E=the voltage gradient =the frequency e'=the dielectric constant a=the loss angle.

4 Where the material is being treated between electrodes, and where a series dielectric such as an air gap is present, the formula becomes:

BEZfe Atan itHera-cica@mi Where I B=a constant E, f, e', as defined above e1=the dielectric constant of the series dielectric k=the ratio of the space occupied by the material to the total space occupied by the material and the series dielectric (spacing factor).

In a practical system comprising an oscillator, electrodes, and the material to be heated by the eld between the electrodes, where such material is present in series with another dielectric, Equation 2 can be applied only as a general guide in ascertaining the optimum values of the electrical characteristics .e' and tan of the material because of the effect of other variables which affect the strength and configuration of the electric field. Experience, however, has shown that the best conditions for heating a mass of stiifener material incorporated into the upper of a shoe would exist where the dielectric constant e' lies in the range of about 1-3 or somewhat higher and the loss factor tan lies in the range of 0.7-2.0. Although these represent optimum values, a stiffener composition having a tan of on`.y about `.01 can be softened and cured if the leather of the upper is dry.

While the aldehyde resins which I have found suitable for use in preparing a stiffener blank have sufficient values for e' and tan for proper heating in a high-frequency electric leld, I have found that the heating rate of the mass of stiiener material can be increased both absolutely and also relatively to the heating of the upper leather by the addition .to the stiiener material of as little as .5% of a substance which has a tan greater than that of the resn in the stiener material. Additionally, the substance should be nonreactive with the resinous material lest by chemical association the dielectric loss of the material be lowered. Conveniently the substance may be an organic compound, for example, ethylene glycol.

The addition of organic compounds to material in large quantities' may tend to adversely affect the quality of the finished stiflener and, accordingly, it is preferred to limit the amount of an added organic compound to less than about 15% of the combined resin and compound, that is, less than about 18% by weight of the resinous material.

Limp stiffener blanks, for example, a toe stiffener blank (Fig. 1) and a counter stiiener blank (Fig. 2), may be incorporated in the upper of a shoe `at any suitable stage in the manufacture of the shoe. Conveniently the blanks may be incorporated in and become part of the upper during the assembling of the parts of the upper in the stitching room. The upper may then go through the regular'shoe-manufacturing operations, including beingmounted upon and conformed to a last; and, at any time after the lasting has been completed, the toe and heel ends of the upper, with the conformed, limp stiiener therein, may be subjected to the heating eiect of a high-frequency i'leld.

The stiiening material, as has been stated. is

preferably incorporated in selected portions of the upper by incorporating two separate stiffener blanks such as are shown in Figs. 1 and 2. In Fig. 6 a lasted upper is indicated at |00, a stiffener at 200, a lining at 300, and a last at 400. After the stiffeners have been incorporated in the upper and the upper has been lasted, the next step is to subject the selected portions of the upper to the heating effect of a high-frequency field. A convenient method of accomplishing this will now be described in connection with a suitable apparatus.

Referring first to Figs. 3 and 4, the apparatus comprises a base 9 upon which are mounted a front section and a rear section. The front section comprises a block II which is hollowed out to receive a flexible rubber bag I3 shaped to receive the toe portion of a lasted shoe, said block being adjustable toward and from the rear section in a guideway I5 formed in the base 9 and held in adjusted position by a clamping screw I1, the purpose of this adjustment being to provide for shoes of different lengths. The rear section also has a flexible bag I9 which is shaped to extend around the rear and sides of the shoe, and the wings or sides of which can be moved from open to closed position. Two electrode holders 2 I, 23, the details of construction of which will be described later, are placed respectively upon the toe portion and the rear portion of the upper on the lasted shoe, and then the lasted shoe, with the electrode holders in place upon it, is placed as shown in Figs. 3 and 4 with the electrode holder 2I resting against the bag I3 and the electrode holder 23 resting against the bag I9, the block II having been adjusted horizontally and locked in position by the clamping screw I1. A cover 25, which is hinged to the front section at 21, is swung over and down into horizontal position and fastened in this position by a hasp (not shown) on the cover, the slot in the hasp receiving a staple (not shown) driven into the block II, a pin (not shown) being passed through the staple to hold the hasp in place. The cover 25 (Fig. 7) has set into it near its middle a block of resilient material 29 which presses down the electrode holder on the toe portion of the shoe. A similar cover 3I (Fig. 3), hinged to a stationary part of the rear section at 33, is swung over and its hasp (not shown) held by a staple 35 which is driven into a stationary part of the rear section. This cover 3I (Fig. 6) has set into it near its middle a block of resilient material 31 which presses the electrode holder 23 and the rear portion of the lasted shoe against the flexible bag I9. Next, the sides or wings of the rear bag I9 are forced inwardly in a manner presently to be described so as t0 press the sides or wings of the rear electrode against the upper and the upper against the sides of the rear portion of the last.

In the manufacture of shoes it is usual to tack an insole to a last, the heel end of the insole being somewhat narrower than the widest part of the rear end of the last so that there is a re-entrant angle which extends around the heel end of the last and insole, said angle (Fig. 6) being bounded on one side by the edge of the insole 500 and on the other by the somewhat curved surface at the bottom of the heel end of the last. It is desirable that the finished stiffener should bridge this angle; and in order that the stiffener, while soft, shall not be forced into this angle, the inner wall of the bag at this locality is given suillcient rigidity. In the illustrated construction there is vulcanized or otherwise attached to the adjacent portion of the inner wall of the bag I9 a strip of resilient material 39, wedge-shaped in cross section, so that no objectionable crease or depression appears in the outer of the finished shoe.

With the shoe and the electrodes thus rmly held, a fluid under pressure, for example, compressed air, is forced through two pipes II and 43 into the rear bag I9 and through the pipe 45 into the front bag I3 to distend the bags. Thereafter the electrodes are energized from the terminals of an oscillator whereby the stiffening material is caused to soften and cure to a hard and resilient condition. The purpose of the pressure is twofold. First, it presses the electrodes, which are flexible, firmly into contact with the shoe, thereby rendering the'n much more effective. Second, it presses the outer, the stiffening matrial, and the lining of the shoe into firm contact with each other so that the three members are firmly bonded together in the finished shoe.

Although the pressure applied by the bags serves to press together the outer, the stiffening material and the lining to facilitate bonding, it has been found that adequate bonding is ordinarily obtained without external pressure by the pressure exerted between the lasted oxer upper and the last.

The general construction and mode of operation having been given above, a detailed description of the parts of the apparatus will be found in United States Letters Patent No. 2,406,738, the patent on the divisional application referred to above.

Example I Parts by weight Paraplex X 40 Durez Resin #12687 70 Benzoyl peroxide 1 AltaX 1 Titanox R. A. 10MO 50 Acetone 134 Methanol 24 Paraplex X100, put out by the Resinous Products & Chemical Co. of Philadelphia, Pa., is an alkyd type thermosetting resin having a. softening range of from 100 F. to 105 F. Durez Resin #12687 is a thermosetting phenolformaldehyde resin, put out by Durez Plastics & Chemicals, Inc., of North Tonawanda, New York, which has a softening range of 40-60 C. and a `,melting range of 70-75 C. Benzoyl peroxide is an accelerator for the curing of the thermosetting resinous material. Altax, benzothiazyl disulfide, put out by the R. T. Vanderbilt Co., of New York, N. Y., is a rubber accelerator but here probably acts to retard somewhat the curing operation. Titanox R. A. 10MO is a titanium oxide put out by the Titanium Pigment Corporation of New York, N. Y. It serves here principally as a filler. A cotton duck blank was impregnated with the solution, dried, subjected to flexing, forming a limp, dry, stiffener blank which was then incorporated into the upper of a shoe and subjected to a highfrequency electric field. Upon cooling, a stiff resilient toe was obtained.

Example II Parts by weight Penacolite B-l 40 Hexamethylenetetramine 4 Methanol 40 Penacolite B-1, put out by Koppers Co. of Pittsaldehyde resin. Hexamethylenetetramine is a reactant for the curing or the thermosetting resinous material.

A blank of cotton duck was impregnated with g Example IX the solution, dried, and incorporated in the upper Parts by weight or a shoe. The shoe was treated for twelve sec- UfOl'mite F200E 100 onds in a high-frequency electric neld giving a P-198 Beckamine accelerator 5 stiff resilient box. A Butyl almh' o 50 Other solutions which may be used in the torl0 mation of stiiiener blanks which may be used for Ufol'mlte F200E 1S an alkylated Urea resin stiiening shoes in the manner described above 50% selld in (1'1 zylol and butyl 81001101) Put are: out by the Resinous Products and Chemical Co..

Example III oi Philadelphia,Pa. Parts by weight i6 GE No. 12315 '15 Example X Parts byweight 112222216X X100 35 Urormim/ms 10o y1 peroxide 1 Acetone 80 Butyl alcohol 55 Methanol 8o 20 P-198 Beckamine accelerator 5 GE No. 12315, put out by the General Electric Uformite MM-55 is a. 50% solution oi a thermo- Co. of Schenectady, N. Y., is a two-stage phenosetting melamine-formaldehyde resin, in a 1 to lic-formaldehyde resin. 4 mixture of zylol and butyl alcohol, put out by Example IV 25 the Resinous Products and Chemical Co., of Parts by weight Philadelphia. Pa. Bakelite BR16190 ,m Having described my invention, what I claim Hexamethylenetetramme lo as new and desire to secure by Letters Patent Acetone 50 of the United States is: Methanol 50 3o 1. In a method of producing a stiiening portion in a. shoe, the steps comprising incorporat- Bakelite BR16190, put out by the Bakelite Cormg in o, goleoted portion of the opper ln un- D01'91ti0n 0f New YOrk. N Y, iS a two-stage resorheated, dry, limp form, a thermosetting resinous cinol type of thermosetting resin. material which is soft or iluid when heated, as-

Emamplo V u sociating said upper with a sole member and parts by welght conforming the upper to a last, and thereafter, lBakou/ 33,1754@ go while holding the upper so conformed, subjecting paraplox Xloo 2o the selected portion to the heating eiect of a Hexamethylenetramine high-frequency electric w cure the resinous Boozoyl peroxide l o material and bond it to the upper. Aootono 75 -2. The method of claim 1 in which the ma- Methanol 75 terial is an aldehyde resin. 3. The method of claim 1 in which the ma- Bakelite BR17540, put out by the Bakelite Cortonal ls a ureaformaldehyde mslm poration, is a phenolic type of thermosetting 45 `.1 The method of claim 1 ln which the malleslnterial is a melamineformaldehyde resin.

Example VI 5. In a, method of producing a stiilening por- Pe'l'ts by Welght tion in a shoe, the steps comprising incorporating Bakelite :Bl-M6190 85 ia selected portion of the upper in unheated, Ethylene glycol l2 5o dry, limp form a layer of thermosetting resinous Acetone 70 material which is soft or iiuid when heated, con- Methanol 70 forming said portion to the shape in which it The ethylene glycol ls employed to lool-ease the is to be stiffened and while holding said portion rate of heating of the stlllenor material by the so conformed, subjecting 1t to the heating effect eleotrlo nolo. 55 of -a high frequency electric field to cure the Example V11 resinous material and bond it to the upper.

. Parts by weight JOHN J. BROPHY. Penacolite B-1 30 Diethyl amine 3 REFERENCES CITED Methanol 70 e0 The following references are of record in the Here the diethyl aminev is used to increase the iile of this patent: rate of dielectric heating.

Example V111 UNITED STATES PATENTS Parts by weight o5 Number Name Date Bekamine NO- 364 100 2,167,874 Cordier Aug, 1, 1939 Water 200 P-198 Beckamine accelerator 5 Beckamine No. 364 is a 'I3-77% dispersion in watero! a urea-formaldehyde resin put out by ll'teichhold Chemical Co.. of Detroit, Michigan. 

